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#1
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Need help with noise insulation in aluminum hull
Guys,
I ahve a 19 ft aluminum boat. It has an inboard jet with a Merc 200 HPO powerhead. The motor is under a doghouse .. 1/8 aluminum with bubble wrap insulation. The motor is very loud. Some noise comes from, the entiure hull vibrating but most comes from the doghouse which also isnt airtight... I am planing to line it with soundown dampener and put decoupler foam over it. ... Unfortunately I cant get ahold of them by phone or email.. Can anybody please help? I am wondering how heavy the dampener layer has to be for the 2 stroke nopise? weight is an issue so I am hopeing .5 - 1 lb/ft2 will do ... How heavy and think of a foam/decoupler layer will i need? will 0.5 lb/ft2 with 2-3" foam do? Any advice appreciated Matt |
#2
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#3
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have that on the putside of the doghouse but want some more for the
inside |
#4
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http://www.auralex.com/sound_isolati...heetblokPL.asp
1#/ft2 as per site. Making it airtight will greatly help reduce noise, but I am unsure of the fire issues. Sound transmission is affectly greatly by mass. It may not be the purtiest looking but I bet cement board would be the most cost effective/fire proof. |
#5
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Airtight is good, but you do have to move enough air in and out of the box
to keep the engine from slagging down. I don't think the oil and water cooling are enough especially for accessories like the alternator. Roger http://home.earthlink.net/~derbyrm wrote in message ups.com... http://www.auralex.com/sound_isolati...heetblokPL.asp 1#/ft2 as per site. Making it airtight will greatly help reduce noise, but I am unsure of the fire issues. Sound transmission is affectly greatly by mass. It may not be the purtiest looking but I bet cement board would be the most cost effective/fire proof. |
#6
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Hi
New to here, saw you are looking for a way to reduce noise from your engine room. There is a system sold that is quite effective but can be a bit high in price, Sound Down (not the floor under lay) a marine system sold out of Maine or mass. The system has two layers of high density foam with a thin sheet of lead laminated between them. The foam laminate is attached to deckheads, bulkheads and hull surfaces in the engine room. It is then covered with a perforated aluminum diffuser plate. The purpose of the diffuser plate is to break up the sound waves before they enter the foam to be absorbed. One of the things I think you are looking for is a cost effective way to do this task, sound down systems would most likely not be the product for you. If you want to MacGyver a system just make some substitutions and you should have a good level of success. Any acoustic dampener such as the panels used in out-door theaters (I believe they are water resistant) attached to the deckheads or bulkheads covered with a 1/16" aluminum sheet would do the trick. Space the aluminum sheet 1/8" away from the panel to allow the sound waves the area the need to disperse. The aluminum plates should have 1/8' holes drilled on one inch centers or less. The tighter the hole pattern the better the system will work. If you are using the system in an area where you have need of a finished living area surface you can strap over the aluminum and attach your desired finish surface to the strapping. This type of system can be installed in just the machinery areas or through out the vessel depending on your need. Doug "Roger Derby" wrote in message ink.net... Airtight is good, but you do have to move enough air in and out of the box to keep the engine from slagging down. I don't think the oil and water cooling are enough especially for accessories like the alternator. Roger http://home.earthlink.net/~derbyrm wrote in message ups.com... http://www.auralex.com/sound_isolati...heetblokPL.asp 1#/ft2 as per site. Making it airtight will greatly help reduce noise, but I am unsure of the fire issues. Sound transmission is affectly greatly by mass. It may not be the purtiest looking but I bet cement board would be the most cost effective/fire proof. |
#7
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Djinning up your own system is a good idea, but lead is MUCH more effective
than aluminum. Steel would also be better. You are looking for mass and low elasticity so the sound energy gets translated to heat instead of being transmitted. The last thing you want is a diaphragm which resonates at the frequency you are trying to damp. Somewhere in my vast junk pile I have a role of sound dampening material sold to aircraft owners. It's a tape with a lamination of tar(?) and lead. Aircraft owners that can afford the weight gain apply it to panels to kill the vibrations. (Greater mass implies lower frequency implies less pain. Rumbles are better than screams.) Roger http://home.earthlink.net/~derbyrm "Doug Christie" wrote in message ... Hi New to here, saw you are looking for a way to reduce noise from your engine room. There is a system sold that is quite effective but can be a bit high in price, Sound Down (not the floor under lay) a marine system sold out of Maine or mass. The system has two layers of high density foam with a thin sheet of lead laminated between them. The foam laminate is attached to deckheads, bulkheads and hull surfaces in the engine room. It is then covered with a perforated aluminum diffuser plate. The purpose of the diffuser plate is to break up the sound waves before they enter the foam to be absorbed. One of the things I think you are looking for is a cost effective way to do this task, sound down systems would most likely not be the product for you. If you want to MacGyver a system just make some substitutions and you should have a good level of success. Any acoustic dampener such as the panels used in out-door theaters (I believe they are water resistant) attached to the deckheads or bulkheads covered with a 1/16" aluminum sheet would do the trick. Space the aluminum sheet 1/8" away from the panel to allow the sound waves the area the need to disperse. The aluminum plates should have 1/8' holes drilled on one inch centers or less. The tighter the hole pattern the better the system will work. If you are using the system in an area where you have need of a finished living area surface you can strap over the aluminum and attach your desired finish surface to the strapping. This type of system can be installed in just the machinery areas or through out the vessel depending on your need. Doug "Roger Derby" wrote in message ink.net... Airtight is good, but you do have to move enough air in and out of the box to keep the engine from slagging down. I don't think the oil and water cooling are enough especially for accessories like the alternator. wrote in message ups.com... http://www.auralex.com/sound_isolati...heetblokPL.asp 1#/ft2 as per site. Making it airtight will greatly help reduce noise, but I am unsure of the fire issues. Sound transmission is affectly greatly by mass. It may not be the purtiest looking but I bet cement board would be the most cost effective/fire proof. |
#8
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the aluminum is only used as a diffuser plate the sound dampening is
performed by the acoustic panel used, most of which have a lead lining. "Roger Derby" wrote in message ink.net... Djinning up your own system is a good idea, but lead is MUCH more effective than aluminum. Steel would also be better. You are looking for mass and low elasticity so the sound energy gets translated to heat instead of being transmitted. The last thing you want is a diaphragm which resonates at the frequency you are trying to damp. Somewhere in my vast junk pile I have a role of sound dampening material sold to aircraft owners. It's a tape with a lamination of tar(?) and lead. Aircraft owners that can afford the weight gain apply it to panels to kill the vibrations. (Greater mass implies lower frequency implies less pain. Rumbles are better than screams.) Roger http://home.earthlink.net/~derbyrm "Doug Christie" wrote in message ... Hi New to here, saw you are looking for a way to reduce noise from your engine room. There is a system sold that is quite effective but can be a bit high in price, Sound Down (not the floor under lay) a marine system sold out of Maine or mass. The system has two layers of high density foam with a thin sheet of lead laminated between them. The foam laminate is attached to deckheads, bulkheads and hull surfaces in the engine room. It is then covered with a perforated aluminum diffuser plate. The purpose of the diffuser plate is to break up the sound waves before they enter the foam to be absorbed. One of the things I think you are looking for is a cost effective way to do this task, sound down systems would most likely not be the product for you. If you want to MacGyver a system just make some substitutions and you should have a good level of success. Any acoustic dampener such as the panels used in out-door theaters (I believe they are water resistant) attached to the deckheads or bulkheads covered with a 1/16" aluminum sheet would do the trick. Space the aluminum sheet 1/8" away from the panel to allow the sound waves the area the need to disperse. The aluminum plates should have 1/8' holes drilled on one inch centers or less. The tighter the hole pattern the better the system will work. If you are using the system in an area where you have need of a finished living area surface you can strap over the aluminum and attach your desired finish surface to the strapping. This type of system can be installed in just the machinery areas or through out the vessel depending on your need. Doug "Roger Derby" wrote in message ink.net... Airtight is good, but you do have to move enough air in and out of the box to keep the engine from slagging down. I don't think the oil and water cooling are enough especially for accessories like the alternator. wrote in message ups.com... http://www.auralex.com/sound_isolati...heetblokPL.asp 1#/ft2 as per site. Making it airtight will greatly help reduce noise, but I am unsure of the fire issues. Sound transmission is affectly greatly by mass. It may not be the purtiest looking but I bet cement board would be the most cost effective/fire proof. |
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